Patent Literature 1: JP 2007-112303 A
For instance, Patent Literature 1 discloses an anomaly diagnosis system connecting a plurality of apparatus ECUs and a power ECU via a network. The plurality of apparatus ECUs are to perform controls of respective apparatuses by receiving electric power from an in-vehicle power source; the power ECU is to detect a state of the in-vehicle power source or a power source switching relay. Such a system can specify a reason or occurrence point of a defect, if occurs.
In the anomaly diagnosis system, an apparatus ECU detects a power supply voltage that is provided to the apparatus ECU itself. When detecting a defect such as voltage variation, instantaneous power interruption, or voltage decline, the system stores a diagnostic informational item that indicates the defect. The power ECU collects the diagnostic informational items from the respective apparatus ECUs. If detecting a defect regarding power supply in at least one apparatus ECU, the power ECU tries to detect whether an anomaly occurred at the time of defecting the defect in several check points such as a power supply to each apparatus ECU, a state of the in-vehicle power source, or a state of the power source switching relay. From the comprehensive relation of the detection results of the several points, the power ECU specifies the occurrence point or detailed contents of the defect regarding the power supply and stores the specified informational data in a memory.
Various in-vehicle ECUs have been required recently to execute the various kinds of controls even when the host vehicle is under a stop state. For example, the controls under the vehicle stop state include a “smart key control” to control locking/unlocking of vehicle doors via two-way communications between an in-vehicle apparatus and a portable key, and a “charge control” to control charging in an electric vehicle or a plug-in hybrid vehicle.
The vehicle stop state disables the generation by an alternator or the regeneration brake by an in-vehicle motor. This situation significantly requires the power consumption by each ECU to be decreased to a minimum level. This leads in proposals of technologies that cause each of the various kinds of ECUs mentioned above to enter a sleep mode if unnecessary for controls or cause only some of the ECUs related with a specific control that needs to be activated even under the vehicle stop state.